c-decl.c (implicitly_declare): Diagnose incompatible implicit declarations.

	* c-decl.c (implicitly_declare): Diagnose incompatible implicit
	declarations.

testsuite:
	* gcc.dg/redecl-5.c: New test.
	* gcc.dg/format/attr-6.c: Expect warning for implicit declaration
	of scanf.

From-SVN: r85509

gcc/ChangeLog

+2004-08-03  Joseph S. Myers  <jsm@polyomino.org.uk>
+
+	* c-decl.c (implicitly_declare): Diagnose incompatible implicit
+	declarations.
+
 2004-08-03  Mike Stump  <mrs@apple.com>
 
 	* config/darwin-c.c: Don't search in "/Local/Library/Frameworks"

gcc/c-decl.c

@@ -2082,6 +2082,23 @@ implicitly_declare (tree functionid)
 	      implicit_decl_warning (functionid, decl);
 	      C_DECL_IMPLICIT (decl) = 1;
 	    }
+	  if (DECL_BUILT_IN (decl))
+	    {
+	      if (!comptypes (default_function_type, TREE_TYPE (decl)))
+		{
+		  warning ("incompatible implicit declaration of built-in"
+			   " function %qD", decl);
+		}
+	    }
+	  else
+	    {
+	      if (!comptypes (default_function_type, TREE_TYPE (decl)))
+		{
+		  error ("incompatible implicit declaration of function %qD",
+			 decl);
+		  locate_old_decl (decl, error);
+		}
+	    }
 	  bind (functionid, decl, current_scope,
 		/*invisible=*/false, /*nested=*/true);
 	  return decl;

gcc/testsuite/ChangeLog

+2004-08-03  Joseph S. Myers  <jsm@polyomino.org.uk>
+
+	* gcc.dg/redecl-5.c: New test.
+	* gcc.dg/format/attr-6.c: Expect warning for implicit declaration
+	of scanf.
+
 2004-08-03  Roger Sayle  <roger@eyesopen.com>
 
 	PR middle-end/16790

gcc/testsuite/gcc.dg/format/attr-6.c

@@ -18,4 +18,5 @@ void
 foo (const char *s, int *p)
 {
   scanf("%ld", p); /* { dg-warning "format" "implicit scanf" } */
+  /* { dg-warning "implicit" "implicit decl warning" { target *-*-* } 20 } */
 }

gcc/testsuite/gcc.dg/redecl-5.c

+/* Test for multiple declarations and composite types.  Diagnosis of
+   incompatible implicit declaration.  */
+/* Origin: Joseph Myers <jsm@polyomino.org.uk> */
+/* { dg-do compile } */
+/* { dg-options "-std=c89" } */
+
+void
+f (void)
+{
+  long z(); /* { dg-error "previous implicit declaration" } */
+}
+
+void
+g (void)
+{
+  z(); /* { dg-error "incompatible" } */
+  labs(1); /* { dg-warning "incompatible" } */
+  printf("x"); /* { dg-warning "incompatible" } */
+}